Thermostatically operated valve assembly

ABSTRACT

A thermostatically operated valve assembly including a pair of valves in a cascade arrangement with one of the valves being a relatively small flow valve movable between closed and opened positions with a snap action in accordance with minor temperature variations and with a relatively larger valve being provided with a gradual opening movement in accordance with major temperature variations.

United States Patent Katchka 1451 Aug. 8, 1972 [54] THERMOSTATICALLYOPERATED 3,159,346 12/1964 .Caparone et a1 ..236/48 X VALVE ASSEMBLY3,190,314 6/1965 Visos et al. ..236/48 X 3,236,262 2/1966 Dobbin..236/48 X [72] Invent Jay 1mg Beam 3,275,035 9/1966 Freeby et a1..236/48 x [73] Assignee: Robertshaw Controls Company,

Richmond, Va. Primary Examiner-William F. ODea Assistant Examiner-P. D.Ferguson [22] Filed 1970 Attomey-Auzville Jackson, Jr., Robert L. Marben[21] Appl. No.: 243 and Anthony A. O'Brien [52] US. Cl ..236/48 R,137/630.15, 251/75 [57] ABS CT 51 1111. c1. ..'.....G05d 23/10 A h pyoperated valve assembly mcludmg 581 Field of Search ..137/630.14,630.15; 236/48; 3 P of valves m a caspade arrangement wlth one of 251/75the valves bemg a relatlvely small flow valve movable between closed andopened positions with a snap action in accordance with minor temperaturevariations [56] References cued and with a relatively larger valve beingprovided with UNITED STATES PATENTS a gradual opening movement inaccordance with 2,073,168 3/1937 Newell ..236/48 x temperature vanamns'2,889,990 6/1959 Loveland et a1. ..236/48 6 Claims, 3 Drawing FiguresIIIIIIIIIIIII IIA III.

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PATENTEDAus 8 I972 FIG. I

INVENTOR, Jay R. Korchkc BY W 74.

ATTORNEY THERMOSTATICALLY OPERATED VALVE ASSEMBLY BACKGROUND OF THEINVENTION springs for the two separate valve elements with the resultthat a high spring force is applied to the main valve and a low springforce is applied to the smaller or supplemental valve.

SUMMARY OF THE INVENTION It is, therefore, an object of the presentinvention to improve prior art devices in such a manner that a highspring force is applied to both large and small valves for closurethereof.

This invention has another object in that a single high force spring isutilized to affect closure of a pair of concentrically arranged valves.

A further object of this invention is to reduce the possibility ofleakage through a pair of valves in a cascade arrangement.

It is another object of the present invention to open the smaller ofserially arranged valves with a snap action and to open the larger ofsuch valves with a gradual movement.

The present invention is summarized in a thermostatic control deviceincluding a casing having inlet and outlet ports with a flow passagetherebetween, a main valve movable between opened and closed positionsfor controlling a main flow through such passage, a supplemental valvecarried by the main valve to permit a supplemental flow through suchpassage when the main valve is in its closed position, a snap actingmechanism for operating the main and supplemental valves, thermalresponsive means operatively connected to the snap acting mechanism formoving it between actuated and released positions in accordance withtemperature variations, the snap acting mechanism having an initial snapmovement applying an impact force on the supplemental valve for openingit with a snap action and having a subsequent gradual movement applyinga gradually increasing force on the main valve for opening it with agradual action, and spring means biasing both the main and supplementalvalve to closed positions when the snap acting mechanism is released bythe thermal responsive means.

Other objects and advantages of the present invention will becomeapparent from the following description taken in conjunction with theaccompanying draw- BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a sideelevation view of a thermostatically controlled device with parts brokenaway'and parts in section embodying the present invention;

FIG. 2 is an enlarged section of a detail of Fig. l but showing it inanother controlling position; and

Fig. 3 is similar to Fig. 2 but showing the components in still anothercontrolling position.

DESCRIPTION OF THE PREFERRED EMBODIMENT As is illustrated in Fig. 1, thepresent invention is embodied in a thermostatic control device includinga casing, indicated generally at 10, having an inlet port 12 forreceiving fuel from a gas source (not shown) and an outlet port 14 fordelivering fuel to burner apparatus (not shown). Such control devicesconventionally include a second outlet port for delivering a smallerflow of fuel to a pilot burner of the burner apparatus wherebythermostatic cycling thereof is permitted due to the pilot burner flamewhich effects reignition; a manually resettable thermoelectric safetydevice is retained in a flow permitting position in response to thepilot burner flame and shuts off all fuel flow upon extinguishment ofthe pilot burner flame. Since any type of pilot flow control device maybe utilized, a detailed description is being omitted for the sake ofbrevity.

The flow of fuel into the casing 10 is controlled by a manually operatedon-off valve 16 disposed adjacent the inlet port 12, as is well known inthe art; the downstream side of the on-off valve 16 communicates with aninlet chamber 18, from which the fuel flow to the outlet port 14 isthermostatically controlled. A temperature selection dial 20 is mountedon the external end of an adjusting shaft 22 which is threaded through abushing fixed to a front wall of casing 10. Shaft 22 is axially movablein a sleeve 24 extending across the flow passage adjacent the outletport 14 and being sealed at both ends. The free end of shaft 22 abutsone end of an operating lever 26.

The thermostat for actuating the lever 26 includes a conventional rodand tube type in which a rod 28 is concentrically disposed in a tube 30.The tube 30 is made of material that has a relatively high coefficientof thermal expansion while the rod 28 is made of material that has arelatively low coefficient of thermal expansion. The tube 30 has athreaded end for fastening it to the mounting shank 32 of the casing 10and the opposite end of the tube 30 is fixed to the adjacent end of therod 28 whereby the rod 28 follows the longitudinal movement of the tube30 due to thermal expansion and contraction. The free end of the rod 28engages the lever 26 intermediate its ends while the other end of lever26 engages an operating button 34. It should be noted that any othersuitable type of thermostatic means may be utilized to cause movement oflever 26 in response to variations in temperature from a desired setpoint of the medium in which the tube 30 is disposed. I

The operating button 34 engages a snap action mechanism sealinglymounted in a recess on the rear wall of casing 10. As is conventionallyutilized in thermostatic control devices, the snap action mechanismincludes a fulcrum disc 36 having a flat surface engaged by theoperating button 34 and an annular knife edge or fulcrum on its oppositesurface adjacent its periphery. A clicker disc 38 has a bowed portioncentrally carrying a headed stud 40 which is disposed adjacent thecentral portions of lever arms 42. For a more detailed description ofthe snap action mechanism, reference is made to the above mentioned US.Pat. No. 3,159,346.

The rear wall recess for the snap action mechanism also has a centrallybored, guide bushing 44 which is concentric with an internal wall ofcasing that defines an annular valve seat 46. The downstream side of thevalve seat 46 defines the flow passage leading to the outlet port 14. Acircular valve member 48 cooperates with the valve seat 46 and isintegrally formed on the end of a cylindrical valve stem 50 that has itsother end slidably mounted in the guide bushing 44. The left end of stem50 (as viewed in Fig. 3) is centrally bored to define a flow chamber 52having an outlet aperture 54 communicating with the outlet flow passageleading to the outlet port 14.

As is illustrated in Figs. 2 and 3, the valve member 48 and the valvestem 50 are integral elements having a generally T-shape configurationin cross section and a rubber facing is affixed to the surface of valvemember 48 for cooperation with the valve seat 46. The peripheral lip ofthe stem chamber 52 is raised to define an annular valve seat 56. Acircular valve element 58 cooperates with the valve seat 56 and isintegrally formed on the end of a valve shaft or plunger 60 that has itsother end slidably mounted in the valve stem 50. The plunger 60 isconcentrically carried by the valve stem 50 and extends through thechamber 52, a shaft bore in stem 50 and the right end of valve stem 50(as viewed in FIG. 2) whereby the end of the valve plunger 60 isdisposed adjacent the snap lever arms 42. Coil spring 62 in the chamber52 surrounds the adjacent portion of valve plunger 60 and is mounted incompression between the bottom wall of chamber 52 and the valve element58. A rubber facing is affixed to the surface of valve element 58 forcooperation with the valve seat 56.

The coil spring 62 is a relatively low force spring that biases thevalve element 58 away from the valve seat 56 toward a valve openposition but mainly the spring 62 assists in holding the larger valvemember 48 closed when the smaller valve element 58 is open. A secondcoil spring 64 is a relatively high force spring mounted in compressionbetween the front wall of casing 10 and that surface of valve element 58which is opposite the surface cooperating with the valve seat 56. Thus,the spring 64 biases the valve element 58 to the valve seat 56 toward avalve closed position. The springs 62 and 64 are disposed along a commonaxis and are in opposition to each other. However, because the spring 64has a higher spring force than the spring 62, the valve element 58 isnormally closed on its valve seat 56; since the valve seat 56 is anintegral part of the valve member 48, the same large spring force causesthe valve member 48 to be normally closed on its valve seat 46 (see Fig.1).

In the following description of a sequence of operation of the abovethermostatic control device, it is assumed that manual on-ofi valve 16is opened permitting a pilot flow of fuel to a pilot burner whichprovides a pilot burner flame for ignition of the main flow of fuelduring thermostatic cycling. At the same time, there is a main flow offuel from the inlet port 12 and through the on-ofi" valve 16 to theinlet chamber 18 whence it is controlled thermostatically according tothe demand sensed by the thermostat 28-30. In addition, it is assumedthat the temperature setting knob 20 has been moved to a selectedtemperature setting e. g., F.) which defines the set point that isdesired to be maintained in the medium sensed by the thermostat 28-30.

The relative positions of the valves 48 and 58 in Fig. 1 represent thesensed thermal condition when there is no demand for burner operation;thus, the thermostat 28-30 is in its expanded condition so there is notsufficient force on operating lever 26 to cause actuation of the snapaction mechanism. As the thermostat 28-30 cools, the tube 30 contractsand the rod 28 is moved inward or to the left as viewed in Fig. l; thecontinued inward movement of rod 28 causes the lever 26 to pivotcounterclockwise about the end of shaft 22. The force on the operatingbutton 34 thus increases moving the fulcrum disc 36; such initialmovement is transmitted to the snap acting disc 38 causing it to moveovercenter and be flexed in a direction opposite to that shown in Fig.1.

Fig. 2 illustrates the respective positions of the valve elements 48 and58 upon completion of the initial movement of the snap acting disc 38.The disc 38 is now flexed to the left causing the arms 42 to move theplunger 60 whereby the supplemental valve element 58 is moved to itsopen position with a snap action. During such snap movement, the forcefrom the snap acting mechanism supplements the biasing force of thelight coil spring 62 to overcome the relatively high biasing force ofthe larger coil spring 64. A relatively small flow of fuel is nowpermitted from the inlet passage 18, past the small valve seat 56,through the flow chamber 52 and the outlet aperture 54 to the outletport 14, thence to the burner apparatus (not shown) where it is ignited.

If the burner apparatus supplies sufficient heat to the medium in whichthe thermostat 28-30 is disposed to cause the thermostat to release thesnap mechanism, the larger coil spring 64 will close the small valve 58on its valve seat 56 to cut off the fuel flow. Thus with only minortemperature variations from the set point fixed by the dial 20, thesmall valve 58 will cycle thermostatically to maintain the desiredtemperature.

If the demand for heat is greater than can be satisfied by the smallvalve 58, the thermostat 28-30 continues its movement to the left (asviewed in Fig. 1). Accordingly, the lever arms 42 of the snap actionmechanism are gradually moved into engagement with the end of valve stem50. Since the width of the lever arms 42 is considerably greater thanthe diameter of the recess in the right end of the valve stem 50, thelever arms do not reach into such recess which only serves the purposeof allowing the end of the valve stem 60 to enter into the end of thevalve stem 50 without restriction due to burrs. The lever arms 42 thusmove the stem 50 causing large valve member 48 to move gradually awayfrom its fixed valve seat 46 to a valve open position. A larger flow offuel is now permitted from the inlet passage 18 and past the valve seat46 to the outlet port 14.

With the additional heat being supplied as a result of the larger valve48 being opened, the thermostat 28-30 will commence to expand whereuponthe movement of the snap action mechanism causes the valves 48 and 58 tothrottle downward from their full open positions of Fig. 3 to theirsmall flow positions of Fig. 2. Further expansion of the thermostat28-30 allows the snap action mechanism to snap overcenter from itsposition of Fig. 2 to its position of Fig. 1 wherein the small valve 58is closed on its valve seat 56 with a snap action.

The above arrangement has the particular advantage that a single coilspring 64 is utilized to close both valves 48 and 58. In addition, thesingle high force spring 64 eliminates the need for a separate spring toclose the small valve 58 whereby leakage possibility past either valveis virtually eliminated. It should be noted that the foregoingterminology of main and supplementary adjectives for the valves 48 and58 is merely arbitrary since such adjectives could be utilized vice versa for such valves.

Inasmuch as the present invention is subject to many variations,modifications and changes in detail, it is intended that all mattercontained in the foregoing description or shown in the accompanyingdrawing shall be interpreted as illustrative and not in a limitingsense.

What is claimed is:

1. In a thermostatic control device, the combination comprising a casinghaving inlet and outlet port means and a flow passage therebetween,

main valve means movable between open and closed positions in said flowpassage for controlling a main flow therethrough,

said main valve means including a fixed valve seat in said casing and amovable valve member cooperating with said fixed valve seat,

supplemental valve means carried by said main valve means to permit asupplemental flow through said flow passage when said main valve meansis in its closed position,

said supplemental valve means including a valve seat on said movablemember and a movable valve element cooperating therewith,

snap acting means operatively disposed adjacent said main andsupplemental valve means,

thermal responsive means operatively connected to said snap acting meansfor moving the same between actuated and released positions inaccordance with predetermined temperature variations,

said snap acting means having an initial snap movement applying animpact force on said supplemental valve means for opening the same witha snap action and having a subsequent gradual movement applying agradually increasing force on said main valve means for opening the samewith a gradual action, and spring means biasing both said main andsupplemental valve means to closed positions when said snap acting meansis released by said thermal responsive means,

said spring means including a pair of coil springs acting in oppositionto each other on opposite sides of said valve element, one of said coilsprings exerting a relatively low biasing force on said valve elementand the other of said coil springs exerting a relatively high biasingforce on said valve element whereby said valve element and said movablevalve member are normally closed on said supplemental valve seat andsaid fixed valve seat, respectively.

2. The invention as recited in claim 1 wherein said movable valve memberincludes a stem having a flow chamber and outlet means from said chambercommunicating with said flow passage downstream of said fixed valveseat, and wherein said supplemental valve means is disposed upstream ofsaid fixed valve seat to control the supplemental flow to said flowchamber.

3. The invention as recited in claim 2 wherein said valve elementincludes a plunger slidably extending through the stern of said movablevalve member whereby said movable valve member and said valve elementare concentrically arranged.

4. In a thermostatic control device, the combination comprising a casinghaving inlet and outlet port means and a flow passage therebetween,

main valve means including a fixed valve seat in said casing and amovable valve member cooperating with said fixed valve seat through saidflow passage,

said movable valve member including a stem having a flow chamber andoutlet means from said flow chamber communicating with said flow passagedownstream of said fixed valve seat,

supplemental valve means carried by said main valve means to permit asupplemental flow through said flow passage when said main valve meansis in its closed position,

snap acting means operatively disposed adjacent said main andsupplemental valve means,

thermal responsive means operatively connected to said snap acting meansfor moving the same between actuated and released positions inaccordance with predetermined temperature variations,

said snap acting means having an initial snap movement applying animpact force on said supplemental valve means for opening the same witha snap action and having a subsequent gradual movement applying agradually increasing force on said main valve means for opening the samewith a gradual action,

said supplemental valve means including a supplemental valve seat onsaid movable valve member defining inlet means for said chamber and avalve element cooperating with said supplemental valve seat to controlthe supplemental flow to said flow chamber,

said valve element including a plunger slidably extending through thestem of said movable valve member whereby said movable valve member andsaid valve element are concentrically arranged,

spring means biasing both said main and supplemental valve means toclosed positions when said snap acting means is released by said thermalresponsive means,

said spring means including a pair of coil springs acting in oppositionto each other on opposite sides of plunger to supplement the relativelylow biasing force to overcome the relatively high biasing force on saidvalve element and hold the same in an open position independently ofsaid movable valve member.

6. The invention as recited in claim 5 wherein said stem is engaged bysaid snap acting means after said valve element is moved to an openposition and is gradually moved relative to said fixed valve seat inaccordance with the gradual movement of said snap acting means.

1. In a thermostatic control device, the combination comprising a casinghaving inlet and outlet port means and a flow passage therebetween, mainvalve means movable between open and closed positions in said flowpassage for controlling a main flow therethrough, said main valve meansincluding a fixed valve seat in said casing and a movable valve membercooperating with said fixed valve seat, supplemental valve means carriedby said main valve means to permit a supplemental flow through said flowpassage when said main valve means is in its closed position, saidsupplemental valve means including a valve seAt on said movable memberand a movable valve element cooperating therewith, snap acting meansoperatively disposed adjacent said main and supplemental valve means,thermal responsive means operatively connected to said snap acting meansfor moving the same between actuated and released positions inaccordance with predetermined temperature variations, said snap actingmeans having an initial snap movement applying an impact force on saidsupplemental valve means for opening the same with a snap action andhaving a subsequent gradual movement applying a gradually increasingforce on said main valve means for opening the same with a gradualaction, and spring means biasing both said main and supplemental valvemeans to closed positions when said snap acting means is released bysaid thermal responsive means, said spring means including a pair ofcoil springs acting in opposition to each other on opposite sides ofsaid valve element, one of said coil springs exerting a relatively lowbiasing force on said valve element and the other of said coil springsexerting a relatively high biasing force on said valve element wherebysaid valve element and said movable valve member are normally closed onsaid supplemental valve seat and said fixed valve seat, respectively. 2.The invention as recited in claim 1 wherein said movable valve memberincludes a stem having a flow chamber and outlet means from said chambercommunicating with said flow passage downstream of said fixed valveseat, and wherein said supplemental valve means is disposed upstream ofsaid fixed valve seat to control the supplemental flow to said flowchamber.
 3. The invention as recited in claim 2 wherein said valveelement includes a plunger slidably extending through the stem of saidmovable valve member whereby said movable valve member and said valveelement are concentrically arranged.
 4. In a thermostatic controldevice, the combination comprising a casing having inlet and outlet portmeans and a flow passage therebetween, main valve means including afixed valve seat in said casing and a movable valve member cooperatingwith said fixed valve seat through said flow passage, said movable valvemember including a stem having a flow chamber and outlet means from saidflow chamber communicating with said flow passage downstream of saidfixed valve seat, supplemental valve means carried by said main valvemeans to permit a supplemental flow through said flow passage when saidmain valve means is in its closed position, snap acting meansoperatively disposed adjacent said main and supplemental valve means,thermal responsive means operatively connected to said snap acting meansfor moving the same between actuated and released positions inaccordance with predetermined temperature variations, said snap actingmeans having an initial snap movement applying an impact force on saidsupplemental valve means for opening the same with a snap action andhaving a subsequent gradual movement applying a gradually increasingforce on said main valve means for opening the same with a gradualaction, said supplemental valve means including a supplemental valveseat on said movable valve member defining inlet means for said chamberand a valve element cooperating with said supplemental valve seat tocontrol the supplemental flow to said flow chamber, said valve elementincluding a plunger slidably extending through the stem of said movablevalve member whereby said movable valve member and said valve elementare concentrically arranged, spring means biasing both said main andsupplemental valve means to closed positions when said snap acting meansis released by said thermal responsive means, said spring meansincluding a pair of coil springs acting in opposition to each other onopposite sides of said valve element, one of said coil springs exertinga relatively low biasing force on said valve element and the other ofsaid coil springs exerting a relAtively high biasing force on said valveelement whereby said valve element and said movable valve member arenormally closed on said supplemental valve seat and said fixed valveseat, respectively.
 5. The invention as recited in claim 4 wherein saidvalve element is supplied with a force by said snap acting means, whenin its actuated position, engaging said plunger to supplement therelatively low biasing force to overcome the relatively high biasingforce on said valve element and hold the same in an open positionindependently of said movable valve member.
 6. The invention as recitedin claim 5 wherein said stem is engaged by said snap acting means aftersaid valve element is moved to an open position and is gradually movedrelative to said fixed valve seat in accordance with the gradualmovement of said snap acting means.